Behavioral, neurochemical and neuroimmune features of RasGEF1b deficient mice

The factor RasGEF1b is a Ras guanine exchange factor involved in immune responses. Studies have also implicated RasGEF1b in the CNS development. It is still limited the understanding of the role of RasGEF1b in CNS functioning. Using RasGEF1b deficient mice (RasGEF1b-cKO), we investigated the impact of this gene deletion in behavior, cognition, brain neurochemistry and microglia morphology. We showed that RasGEF1b-cKO mice display spontaneous hyperlocomotion and anhedonia. RasGEF1b-cKO mice also exhibited compulsive-like behavior that was restored after acute treatment with the selective serotonin reuptake inhibitor (SSRI) fluoxetine (5 mg/kg). A down-regulation of mRNA of dopamine receptor (Drd1, Drd2, Drd4 and Drd5) and serotonin receptor genes (5Htr1a, 5Htr1b and 5Htr1d) was observed in hippocampus of RasGEF1b-cKO mice. These mice also had reduction of Drd1 and Drd2 in prefrontal cortex and 5Htr1d in striatum. In addition, morphological alterations were observed in RasGEF1b deficient microglia along with decreased levels of hippocampal BDNF. We provided original evidence that the deletion of RasGEF1b leads to unique behavioral features, implicating this factor in CNS functioning.

Vaccinia virus induces endoplasmic reticulum stress and activates unfolded protein responses through the ATF6α transcription factor

BACKGROUND

Cell responses to different stress inducers are efficient mechanisms that prevent and fight the accumulation of harmful macromolecules in the cells and also reinforce the defenses of the host against pathogens. Vaccinia virus (VACV) is an enveloped, DNA virus, belonging to the Poxviridae family. Members of this family have evolved numerous strategies to manipulate host responses to stress controlling cell survival and enhancing their replicative success. In this study, we investigated the activation of the response signaling to malformed proteins (UPR) by the VACV virulent strain-Western Reserve (WR)-or the non-virulent strain-Modified Vaccinia Ankara (MVA).

METHODS

Through RT-PCR RFLP and qPCR assays, we detected negative regulation of XBP1 mRNA processing in VACV-infected cells. On the other hand, through assays of reporter genes for the ATF6 component, we observed its translocation to the nucleus of infected cells and a robust increase in its transcriptional activity, which seems to be important for virus replication. WR strain single-cycle viral multiplication curves in ATF6α-knockout MEFs showed reduced viral yield.

RESULTS

We observed that VACV WR and MVA strains modulate the UPR pathway, triggering the expression of endoplasmic reticulum chaperones through ATF6α signaling while preventing IRE1α-XBP1 activation.

CONCLUSIONS

The ATF6α sensor is robustly activated during infection while the IRE1α-XBP1 branch is down-regulated.

Antiobesity, hepatoprotective and anti-hyperglycemic effects of a pharmaceutical formulation containing Cecropia pachystachya Trécul in mice fed with a hypercaloric diet

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Cecropia pachystachya Trécul (Urticaceae), known as embaúba, are used as hypoglycemic and for weight reduction in Brazilian traditional medicine.

AIM OF THE STUDY

This study investigated the effects of a pharmaceutical formulation (ECP20) containing C. pachystachya extract on some metabolic alterations caused by a hypercaloric diet in mice.

MATERIAL AND METHODS

Mice were randomly fed with a standard or hypercaloric diet and orally treated with ECP20 or vehicle for 13 weeks. Subsequently, adiposity, glucose intolerance, and the presence of nonalcoholic fatty liver disease were assessed. Adipose tissue and liver were collected after euthanasia and frozen at -80 °C for histological and antioxidant analyzes. The effect of ECP20 on the differentiation of 3T3-L1 pre-adipocytes was also investigated.

RESULTS

Animals treated with ECP20 showed less weight gain, reduced glycemia, glucose tolerance restored, and hepatoprotective effect. Also, ECP20 presented significant in vivo antioxidant activity. Treatment of 3T3-L1 preadipocytes with ECP20 did not inhibit cellular differencing.

CONCLUSIONS

Therefore, ECP20 presented promising effects in the control of obesity and related disorders. Considering that glucose intolerance and hyperglycemia are strong evidence for the development of type 2 diabetes, the findings corroborated the traditional use of C. pachystachya to treat this disease. The chlorogenic acid and the flavonoids orientin and iso-orientin, present in the extract, might be involved in the activities found.

Inhibition of CSF1R, a receptor involved in microglia viability, alters behavioral and molecular changes induced by cocaine

Different data suggest that microglia may participate in the drug addiction process as these cells respond to neurochemical changes induced by the administration of these substances. In order to study the role of microglia in drug abuse, Swiss mice aged 8-9 weeks were treated with the CSF1R inhibitor PLX3397 (40 mg/kg, p.o.) and submitted to behavioral sensitization or conditioned place preference (CPP) induced by cocaine (15 mg/kg, i.p.). Thereafter, brains were used to evaluate the effects of CSF1R inhibition and cocaine administration on morphological, biochemical and molecular changes. CSF1R inhibition attenuated behavioral sensitization, reduced the number of Iba-1+ cells and increased ramification and lengths of the branches in the remaining microglia. Additionally, both cocaine and PLX3397 increased the cell body to total cell size ratio of Iba-1+ cells, as well as CD68+ and GFAP+ stained areas, suggesting an activated pattern of the glial cells. Besides, CSF1R inhibition increased CX3CL1 levels in the striatum, prefrontal cortex and hippocampus, as well as reduced CX3CR1 expression in the hippocampus. In this region, cocaine also reduced BDNF levels, an effect that was enhanced by CSF1R inhibition. In summary, our results suggest that microglia participate in the behavioral and molecular changes induced by cocaine. This study contributes to the understanding of the role of microglia in cocaine addiction.

Protective and anti-inflammatory effects of acetylcholine in the heart

The innate and adaptive immune systems play an important role in the development of cardiac diseases. Therefore, it has become critical to identify molecules that can modulate inflammation in the injured heart. In this regard, activation of the cholinergic system in animal models of heart disease has been shown to exert protective actions that include immunomodulation of cardiac inflammation. In this mini-review, we briefly present our current understanding on the cardiac cellular sources of acetylcholine (ACh) (neuronal vs. nonneuronal), followed by a discussion on its contribution to the regulation of inflammatory cells. Although the mechanism behind ACh-mediated protection still remains to be fully elucidated, the beneficial immunomodulatory role of the cholinergic signaling emerges as a potential key regulator of cardiac inflammation.

Implication of eIF2α kinase GCN2 in induction of apoptosis and endoplasmic reticulum stress-responsive genes by sodium salicylate

OBJECTIVES

Sodium salicylate (NaSal) can disturb cell viability by affecting the activity of multiple cellular molecules. In this work, we investigated the involvement of stress-responsive kinase GCN2 in regulating cell death and expression of stress genes in mouse embryonic fibroblasts (MEFs) upon exposure to NaSal.

METHODS

Cell viability was assayed using the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) method, and apoptosis was evaluated by annexin V and propidium iodide staining. A polymerase chain reaction (PCR) array approach was used to analyse differential expression of a panel of 84 endoplasmic reticulum (ER) stress-associated genes. Gene reporter assays were carried out to determine activity of ER stress element (ERSE), and the protein levels of activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP) were determined by western blot.

KEY FINDINGS

NaSal treatment resulted in reduction of cellular viability and induction of apoptosis in wild-type but not Gcn2(-/-) cells. Many genes with important functions in protein synthesis/degradation, transcriptional regulation and apoptosis were induced by NaSal and most of these were dependent on GCN2. The activation of ERSE within Ddit3 and the production of CHOP and ATF6 induced by NaSal required GCN2.

CONCLUSIONS

Our data provide evidence for the involvement of GCN2 in apoptosis and gene expression triggered by NaSal, and contributes to the understanding of molecular events occurring in NaSal-treated cells.